Resistance of a wire

Extracts from this document...

Introduction

INTRODUCTION –

An electrical circuit was mounted using a power supply, an ammeter, a voltmeter and a resistor (wire). The voltage and current were worked out for different lengths of the wire using the ammeter (for the current) and the voltmeter (for the voltage). Using the voltage and current recordings, the resistances were calculated for each of the lengths.

AIM –

To investigate the correlation between the length and the resistance of a wire.

DIAGRAM –

PICTURE –

HYPOTHESIS –

I predict that the longer the wire, the greater the resistance. This is because the electrons have to move in a longer distance, making the opposition (resistance) of conductor to the current greater.

Although the results came as initially expected, the experiment could have been improved in some ways. Firstly, the wire could have been stretched more (in the limit), to give the more precise lengths. As the wire wasn’t fully stretched, the length readings could have been wrong, affecting the current and voltage. To prevent the wire from overheating, we should have decreased the power from the power supply, as temperature increase can also affect the results. I think that the number of trials was the ideal and repeating it one more time wouldn’t be much useful (although they would be slightly more accurate).

Apart from that, I can say that the experiment went well and was a fair test. The results lead to a conclusion very similar to the hypothesis, which shows us that everything went as expected.

Found what you're looking for?

Start learning 29% faster today

150,000+ documents available

Just £6.99 a month

or

Here's what a star student thought of this essay

4 star(s)

Response to the question

The writer had approached the question well, overall having a well written report. It was nice that the writer decided to give a brief introduction. However, it then was annoying when not only that there wasn't a list of apparatus ...

Response to the question

The writer had approached the question well, overall having a well written report. It was nice that the writer decided to give a brief introduction. However, it then was annoying when not only that there wasn't a list of apparatus but the diagram didn't clearly show where the wire and ruler where going to be placed.It was good that the writer was able to give a hypothesis before the actual experiment, which shows that the writer knew the knowledge behind the experiment that they were doing and why certain correlations would have occurred. When they mentioned Ohm's law, they should have mentioned the conditions that are needed in order for a material to obey Ohm's law. The writer has a clear and easy graph to follow showing the relation between length of a wire and resistivity, also clearly labelling units of measurements. It was also good that the writer explained the effects of temperature on the wire. The evaluation was written well and explained all the draw backs within the experiment.

Level of analysis

The writer's scientific language was of a high standard. Before starting any experimentation, the writer has explained their thoughts on the experiment which shows that the writer was aware of the science involved within experimentation. When it comes to writing decimal numbers, the writer should have written full stops instead of commas. The writer has got the write concepts in terms of calculations, but they have to make sure that the formulae that they use are correct fully.

Quality of writing

The spelling and grammar are of a high standard. However, the writer should double check over their work to make sure that it all makes sense when it's being read. For example "the greater the length of wire lead to a greater resistance" doesn't make sense when read. The use of technical terms are used correctly. However, if they are recording data, they should make sure that all data is kept on the same page if they can. It makes it easier for a reader to follow.

Related GCSE Electricity and Magnetism essays

My results did not agree fully with my heat theory as they showed slight variations, such as a 14.63 result instead of a result close to 13 for a wire of length 150cm. And a 19.87 result instead of a result close to 18 for a wire of length 200cm.

The constantan wire that I am going to use in the experiment is 60 cm long. So all in all I will have 6 results. On its own theses results are not that accurate, so we do the experiment another 2 times.

This must also mean that the next experiment must also be affected in some way, which might affect the next set of results. Another thing I observed during the experiment was that the size of paper clips and how much room they took up on the coil.

And on the 32 SWG wire, the resistance did not increase proportional to the length of the wire at all. This may have been due to kinks or bends in the wire that were not visible. Or there may have been a fault with the equipment.

This is considerably lighter than any of the other balls I could have used. If a heavier ball was used to find the work done by the floor and the ball with the same experiment, the work done would have come out as higher.

As we are working for one complete turn the time taken for one complete turn is the time period T. T is also calculated by the formula T=1/f Where T is the time period which is the time for one complete turn and f is the frequency which is the amount of complete turns in one second.

These wires work by changing the energy that charged particles that pass through them lose into heat energy. Kettles and hair-dryers contain coils of resistance wire in order to create heat which will enable them to fulfil their purpose. Like resistance wires, resistors are created in order to provide resistance, and many resistors contain resistance wire.

45 75 3 to 5 8 45 75 3 to 5 Average 45 75 3 to 5 2.77 0.383 4.617 8.705 Analysis All anomalous results were circled on the graphs. All graphs were checked for direct proportion and if they were it was written in the bottom right corner, and the point, which it became untrue, was also written down.